There has been consternation, bewilderment and mirth from many sides as the British Government's concept of "Covid marshals" has been rolled out in the past month. The idea has also been taken on by South Australia.
When we come across any new official role, an etymological consideration of the title of the role is always an excellent start in working out what the plan is.
British and Commonwealth subjects' first reaction to the the term "marshal" is often that it sounds an American concept. It is actually French in origin.
First of all, the apparent similarity of the noun marshal to the adjective martial (as in "martial law") is purely a phonological coincidence. The etymology of martial is Latin, meaning "of Mars", and hence "warlike". As well as being a noun, marshal has developed into a verb, as in "to marshal one's thoughts".
Marshal is a purely Continental European term in origin and has never been a common-law office. It originates in the Frankish realm. The mare-schalk was the official who stewarded (schalk, "attendant") the royal stables ("mare[s]") while the king and his knights were off riding the stallions in their wars of aggression. After a couple of centuries, the term came to mean "the de-facto administrator of court", not just of the stables.
This development was ongoing at the time when the Normans arrived in France, took over the language (including the term marshal) and then conquered England. Hence, the first meaning that marshal (in the French form maréchal) had in mediaeval England was "cavalry officer". The Frankish idea of the marshal being the real ruler of the kingdom (the embryonic Permanent Civil Service?) is well seen in the life of William, who notably was still called William the Marshal; marshal was still an office rather than a surname. William the Marshal steered the legislation of several reigns and was King John's main stooge against the barons at Runnymede in 1215.
By the time of French military hegemony of Europe in the seventeenth century, the maréchal was not just a cavalry officer but had broadened to mean "supreme field commander above the generals"; the continuity in meaning here from earlier century is that the marshal was a singular figure and resided at court. There were not marshals around the country; there was the marshal in the palace.
A century later, the United States declared independence and consciously copied French military practice. Moreover, the US Constitution and particularly the Second and Tenth Amendment deliberately placed the federal authorities in the weaker position vis-à-vis the states and their militias.
For this reason, the term has developed in the USA more extensively than in Britain or the Commonwealth and has come to mean "representative of federal power", hence the coining of the term "federal marshal" as far back as 1789 for a body of men who protected federal judges from local people disgruntled at impositions of federal law. Federal marshals, employees of the Department of Justice, remained a little-known office of the United States Government until their high-profile deployment aboard aircraft after 9/11. More recently, it was inadvertently revealed that the US Marshals used more phone trackers than any other department of government.
From the American development of the term in particular, we see that a marshal as conceived of by central government is an enforcer of unpopular decisions taken in the capital.
Throughout the modern era, no British or Commonwealth realm had any use for the office of "marshal" on its own, other than in the meaning of "field-marshal" borrowed from French and the derived meaning of "master of ceremonies", and — with the founding of the Royal Air Force in the First World War — the three-star general rank of Air Marshal by analogy with the Army. The plain term marshal is only encountered in British English again from the mid-twentieth century to mean "a chap waving his arms about officiously at a village gathering", hence parking marshal, event marshal and the like. (At boarding school in the 1990s, my comrades and I were yelled in and out of the chapel pews every morning, by year group, by a redoubtable figure known as the School Marshal.)
I conclude that the intent behind the choice of the term "Covid marshal" by Her Majesty's Government in 2020 is to impress pretended central authority upon local people and structures. One could almost regard the term "marshal" as meaning "anti-sheriff" or "overrider of common law".